#include "stdafx.h"
#include "resource.h"

#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;        // current instance
TCHAR szTitle[MAX_LOADSTRING];        // The title bar text
TCHAR szWindowClass[MAX_LOADSTRING];
HBITMAP hbmp;
HDC mdc;
// The title bar text

// Foward declarations of functions included in this code module:
ATOM    MyRegisterClass(HINSTANCE hInstance);
BOOL    InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK About(HWND, UINT, WPARAM, LPARAM);
void MyPaint(HDC hdc);

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
  // TODO: Place code here.
 MSG msg;
 HACCEL hAccelTable;

 // Initialize global strings
 LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
 LoadString(hInstance, IDC_CH2_5, szWindowClass, MAX_LOADSTRING);
 MyRegisterClass(hInstance);

 // Perform application initialization:
 if (!InitInstance (hInstance, nCmdShow))
 {
  return FALSE;
 }

 hAccelTable = LoadAccelerators(hInstance, (LPCTSTR)IDC_CH2_5);

 // Main message loop:
 while (GetMessage(&msg, NULL, 0, 0))
 {
  if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
  {
   TranslateMessage(&msg);
   DispatchMessage(&msg);
  }
 }

 return msg.wParam;
}
void MyPaint(HDC hdc)
{
 BitBlt(hdc,0,0,600,450,mdc,0,0,SRCCOPY);
}

//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
//  COMMENTS:
//
//    This function and its usage is only necessary if you want this code
//    to be compatible with Win32 systems prior to the 'RegisterClassEx'
//    function that was added to Windows 95. It is important to call this function
//    so that the application will get 'well formed' small icons associated
//    with it.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
 WNDCLASSEX wcex;

 wcex.cbSize = sizeof(WNDCLASSEX);

 wcex.style   = CS_HREDRAW | CS_VREDRAW;
 wcex.lpfnWndProc = (WNDPROC)WndProc;
 wcex.cbClsExtra  = 0;
 wcex.cbWndExtra  = 0;
 wcex.hInstance  = hInstance;
 wcex.hIcon   = LoadIcon(hInstance, (LPCTSTR)IDI_CH2_5);
 wcex.hCursor  = LoadCursor(NULL, IDC_ARROW);
 wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
 wcex.lpszMenuName = (LPCSTR)IDC_CH2_5;
 wcex.lpszClassName = szWindowClass;
 wcex.hIconSm  = LoadIcon(wcex.hInstance, (LPCTSTR)IDI_SMALL);

 return RegisterClassEx(&wcex);
}

//
//   FUNCTION: InitInstance(HANDLE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   HWND hWnd;
   HDC hdc;

   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow("ranranyingai", "绘图窗口", WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

   if (!hWnd)
   {
      return FALSE;
   }
   MoveWindow(hWnd,10,10,600,450,true);
   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   hdc=GetDC(hWnd);
   mdc=CreateCompatibleDC(hdc);

   hbmp=(HBITMAP)LoadImage(NULL,"DSC00819.bmp",IMAGE_BITMAP,600,450,LR_LOADFROMFILE);
   SelectObject(mdc,hbmp);

   MyPaint(hdc);
   ReleaseDC(hWnd,hdc);

   return TRUE;
}

//
//  FUNCTION: WndProc(HWND, unsigned, WORD, LONG)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND - process the application menu
//  WM_PAINT - Paint the main window
//  WM_DESTROY - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
 int wmId, wmEvent;
 PAINTSTRUCT ps;
 HDC hdc;
 TCHAR szHello[MAX_LOADSTRING];
 LoadString(hInst, IDS_HELLO, szHello, MAX_LOADSTRING);

 switch (message)
 {
  case WM_COMMAND:
   wmId    = LOWORD(wParam);
   wmEvent = HIWORD(wParam);
   // Parse the menu selections:
   switch (wmId)
   {
    case IDM_ABOUT:
       DialogBox(hInst, (LPCTSTR)IDD_ABOUTBOX, hWnd, (DLGPROC)About);
       break;
    case IDM_EXIT:
       DestroyWindow(hWnd);
       break;
    default:
       return DefWindowProc(hWnd, message, wParam, lParam);
   }
   break;
  case WM_PAINT:
   hdc = BeginPaint(hWnd, &ps);
   MyPaint(hdc);// TODO: Add any drawing code here...
   RECT rt;
   GetClientRect(hWnd, &rt);
   DrawText(hdc, szHello, strlen(szHello), &rt, DT_CENTER);
   EndPaint(hWnd, &ps);
   break;
  case WM_DESTROY:
   DeleteDC(mdc);
   DeleteObject(hbmp);
   PostQuitMessage(0);
   break;
  default:
   return DefWindowProc(hWnd, message, wParam, lParam);
   }
   return 0;
}

// Mesage handler for about box.
LRESULT CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
 switch (message)
 {
  case WM_INITDIALOG:
    return TRUE;

  case WM_COMMAND:
   if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
   {
    EndDialog(hDlg, LOWORD(wParam));
    return TRUE;
   }
   break;
 }
    return FALSE;
}


这是源代码，编译通过但是连接是出现错误：
Linking...
LIBCD.lib(crt0.obj) : error LNK2001: unresolved external symbol _main
Debug/CH2_5.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

CH2_5.exe - 2 error(s), 0 warning(s)
等待高手指点，不胜感激！